Inductor helix



F. CONRAD INDUCTOR HELIX Feb. 19,1929. 1,702,461

Filed Jan. 27, 1925 INVENTOR Fmnk Conrad w oNE WITNESSES:

Patented Feb. 19, 1929. I

UNITED STATES FRANK CON RAD, OF PITTSBURGH, PENNSYLVANIA,

TRIO & MANUFACTURING COMBAN Y,

ASSIGNOR TO WESTINGHOUSE ELEC- A CORPORATION OF PENNSYLVANIA.

INDUC'IOR HELIX.

Application filed January therein are a minimum.

Another object of my invention is to produce an inductor device adapted for the ready dissipation of heat produced therein by energy losses.

Another object of my invention is to produce a compact glass insulated inductance device.

Another object of my invention is to produce a. well-insulated low-loss inductance device particularly adapted for use in apparatus for generating alternatinig currents at frequencies above 1000 kilocyc es Another object of my invention is to produce an inductance having a' conductor ribbon mounted upon heat-resisting glass insulating means.

Another object of my invention is to produce an inductance device capable of carrying large currents of high voltage at radio frequency.

In the prior construction of inductances adapted to cooperate with radio-frequency generating apparatus numerous difficulties have been experienced.

- It is well known that the energy losses produced by electrostatic and electromagnetic hysteresis increase in frequency, for which reason difii culty has been antici ated in constructing inductances capable o handlin large quantities of electrical energy at the high frequency correspondingto short'electronagnetic wave lengths. It hasbeen found that,at frequencies of 1500.kilocycles or'higher, muchdifiiculty is experienced with the generation of heat in the associated parts'of the structure.

It has been found that henolic condensation product material, such as .micarta has such'high electrostatic and electromagnetic losses that at the higher frequencies, a prohibitive amount of energy is wasted in them, causing an amount of heating which'not infrequently damages the apparatus. This material, which is entirely'satisfactory at medium and long wave lengths, is found very unsatisfactory at short wave lengths. Attempts to use wood as the supporting frame eflects increase very rapidly with 27, 1925. Serial No. 5,049.

work have encountered similar difficulties, the presence of moisture in the wood causes it to have high di-electric and electromag netic hysteresis losses that are troublesome.

Likewise, at these high frequencies, the skin effect, which causes the maximum density of current flow to occur at the surface of the conductor and, in a helix, at the outer surface of the coil, causes the resistance losses to mount to a prohibitively high value, thereby generating undesirable large quantities of heat in the inductance, which-are removed only with difiiculty and which likewise injure the insulating supports upon which it is mounted.

My invention provides a simple construction which provides substantial reductions in the energy losses in a helix and which pro- Ivides a construction much less affected by eat.

Other objects and structural details of my invention will be apparent fromthe following description and the accompanying drawin wherein z i 1 igu're"1" is a view in end embodiment of my invention,

Fig. 2 a view in side elevation of my invention,

Fig. 3 is a view in side elevation of the insulator members of my invention, and

' Fig. 4 is a view in end elevation of an embodiment of my invention adapted to coo erelevation of an .ate'with apparatus using extremely sort wave lengths. e

Referring to Figs. 1 and 2, a set of annular rings 1, f2 and 3 have attached thereto a plurality of grooved cross-pieces 4. A pair'of supporting members 5 are respectively attached 1w end rings 1 and 3. These members are preferably made of wood and'beforeassembly are given a special treatment;

This treatment consists of a. very careful drying in' a heated evacuated -cha Ii 1ber,there by'removin'g ractically all moisture from the vwig cl l e drying treatment is then preferably followed by an immersion in an insulating gum applied-under pressure, the gum being fchosento have the lowest possible dielectric and losses.

Alternatively, the wood may be carefully dried and the surface sealed with a suitable insulating covering. Such construction produces loss within its ody from electromagnetic hysteresis corners. The glass insulator pieces are preferably supported in the grooves in the crosspieces 4. Upon insulating members 6 is wound a helical ribbon conductor 7, the opposite ends bein attached to the glass insuating members y being looped thereabout and the end secured b a suitable bolt and binding post. The rib on form of the conductor provides a lar er surface on the outside of the helix for t e, flow of the currents forced there by the skin effect, and thereby reduces the effective high-frequency resistance and the ener loss, and thereby the heat developed. Tension screws 8, shown in dotted lines in the drawing, are provided whereby pressure can be applied to one of the cross-pieces 4 and-transmitted through an insulator 6 to draw the turns of helix 7 taut.

The insulator members 6 are preferably made in the form shown in Fig. 3, having relatively short sections capable of supp0rting a portiononly of the turns of the helix. By this means, a better distribution is obtained of the pressure strains from the helix which is under tension.

In Fig. 4 is shown a second embodiment of my invention in which the annular rings 1 of the preceding figures are replaced by poly nal wooden supporting pieces 11 to who are attached lengthwise pleces 4 which are similarly treated with an insulating gum as above described. They are also of the same type of construction as are shown in Figs. 1 and 2. Upon cross pieces 4 are similarly sup orted insulatin members 6 as in the prece ing figures. A' elix 7 is similarly wound upon the insulating members. This construction gives a relatively small helix, having the necessary small inductance for the generation of wave lengths of to 100 meters,- which is, at the same time, capable of carrying radio-frequency currents correspondin to energy inputs of 10 to 20 kilowatts. he first embodiment of my invention is adapted to carry currents corresponding to similar powers at wave lengths of 200 to 500 meters.

By the construction of the different embodiments of my invention, I have produced an inductor helix which is capable of carrying relatively large powers of electrical energ at extremely high frequencies and in which the energy losses are relatively small.

While I have shown but two embodiments of my invention in the accompanying drawings, it is capable of various changes and modifications without departing from the spirit thereof, and it is desired, therefore, that only such limitations shall be imposed thereon as are indicated in the prior art or in the appended claims.

I claim as my invention:

1. An inductor device comprising a wooden frame, treated with an insulating moistureexcluding material, Wherebydielectric and hysteresis losses therein are reduced, a plurality of heat-resisting vitreous insulating members supported thereby and having low dielectric and hysteresis loss properties, and a helical conductor thereon.

2. An inductor device comprising a conductive helix and means for reducing heating therein, comprising a wooden frame impregnated with moisture-excluding material,

and glass insulator members thereon supporting said helix.

3. An inductor device comprising a coiled copper ribbon, glass insulating supporting members therefor having high heat-resisting properties, high physical strength and low dielectric loss properties, and a gumtreated wooden frame for supporting said insulating members.

4. An lnductor device comprising a coiled copper ribbon, supporting members therefor comprising glass insulating members having high heat-resisting properties, high physical strength and low dielectric loss properties, a gum -treated wooden frame for supporting said insulating members, a portion of said frame comprising tensioning screws adapted to stretch said ribbon.

5. An inductor device comprising a gum treated wooden frame, a plurality of rectanular glass insulator members carried therey and a coiled copper ribbon positioned thereon, said insulator members having one surface slightly curved, edges adjacent thereto being rounded off, and spacing projections thereon.

6. An inductor device comprising a gumtreated wooden frame, a plurality of rectanular glass insulator members carried therey and a coiled copper ribbon positioned thereon, said insulator members havin one surface slightly curved, edges adjacent t ereto rounded off, and spacing projections thereon, the width of said projections being slightly less than the distance between adjacent turns of said coiled ribbon and the space 8. An inductor device comprising a frame having longitudinally extending mechanically strong members near the exterior thereof and glass insulating members supported throughout their length by said mechanically strong members, a coil Wound upon the exterior faces of said glass members and means for moving at least one of said longitudinally extending members radially to tension said coil.

9. ln electrical apparatus, a helical coil. and a supporting cage comprising supporting elements and disposed longitudinally of the coil, said elements being identical and being identically notched to receive and separately support the convolutions of the coil and means for holding said supporting elements in spaced relationship about the circumterence of said coil and axially ofiset in progressive relationship to each other so that their coil notches will conform to the pitch of the windings of said coil.

10. In electrical apparatus, a helical coil, and a supporting cage comprising substan tially identical supporting elements disposed longitudinally of the coil, said elements being substantially identically notched to receive and separately support the convolutions of the coil, and means for holding said sup porting elements in spaced relationship about the circumference of said coil and axially offset in progressive relationshi to one another, the sum total of such axial 0 sets being equal to the space between the convolutions of said coil.

In testimony whereof, I have hereunto subscribed my namethis 21st day of January. 1925.,

FRANK CONRAD. 

